Opine Synthesis in Wild-Type Plant Tissue

Christou, Paul; Ackerman, Mary C.

doi:10.1104/pp.82.1.218

Cited by 41 publications

(9 citation statements)

References 17 publications

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“…Our experience in inoculating conifer seedlings in this screening study and in more extensive experiments with Agrobacterium-inoculated P. taeda seedlings (to be published elsewhere) indicates that there is an inverse relationship between the degree of stem woodiness and/or plant age and the frequency of gall formation. We have observed that the frequency of gall formation can vary from 0 to about 80% in P. taeda with the same Agrobacterium strain but with plants differing in (6) reported that untransformed cultures of soybean, and to a lesser extent cotton, will synthesize nopaline when grown on medium containing high amounts of arginine. Although the authors state that arginine feeding was necessary for opine production, these data are cited as evidence against the use of opines to confirm transformation.…”

Section: Discussionmentioning

confidence: 98%

Extended Host Range of Agrobacterium tumefaciens in the Genus Pinus

Stomp¹,

Loopstra²,

Chilton³

et al. 1990

Plant Physiol.

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Two-to 4-month-old seedlings of nine pine species (Pinus eldarica Medw., Pinus elliottiI Engelm., Pinus jeffreyi Grev. & Balf ., Pinus lambertiana Dougl., Pinus ponderosa Laws., Pinus radiata D. Don, Pinus sylvestris L., Pinus taeda L., Pinus virginiana Mill), Douglas fir (Pseudotsuaa menziesii (Mirb.) Franco) and incense cedar (Libocedrus decurrens Torr.) were inoculated with five strains of Agrobacterium tumefaciens. Transformation occurred in all conifer species tested as determined by gall formation and opine production. The frequency of gall formation varied by host species, by bacterial strain, and was related to the age of the stem when inoculated. Galls were visible 8 to 12 weeks after inoculation and were small (often less than 2.5 millimeters in diameter). Fewer than half (230 of 502) of the galls originally formed on the trees were present after 1 year, and 26 of these grew to diameters greater than 2 centimeters. The majority of these larger galls (18 of 26) were found in P. radiata. Bacterial strain-specific opines were found in 67 of the 81 gall tissues sampled.Agrobacterium-mediated DNA transfer occurs in many dicotyledonous plants (8) and has considerable potential as a gene vector system ( 18). Realization of this potential is determined, in part, by the efficiency of DNA transfer (13). Transformation efficiency is often established by measuring the frequency of gall formation produced by a specific strain in the plant population, i.e. species, cultivar, or variety, to be transformed (5). Although the host range ofAgrobacterium is extensive in dicots (8), many gymnosperms (8, 23) and most monocots (15) do not readily form galls in response to inoculation. The lack of gall formation has been interpreted as the inability of Agrobacterium to transfer DNA, even though this was shown not to be the case (15).Gall formation is the result of transfer of genes whose expression in transformed cells results in the production of

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Section: Discussionmentioning

confidence: 98%

Extended Host Range of Agrobacterium tumefaciens in the Genus Pinus

Stomp¹,

Loopstra²,

Chilton³

et al. 1990

Plant Physiol.

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“…Because opines are also detectable in non-transformed, wild-type plant tissue (Christou et al 1986), transformation is only documented by the existence of the specific bacterial opine-synthesizing lysopine-dehydrogenase. Second-generation genes include the most frequently used scoreable markers luciferase (LUC) from glowing bacteria (Vibrio harveyi, V.fischeri) and lightning bugs (e.g.…”

Section: Marker and Reporter Genesmentioning

confidence: 99%

Plant Cell Biotechnology

Endreß

1994

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“…This latter compound. however, can be found in the cells of some nontransformed plants (7) and is therefore not a true opine.…”

Section: Methodsmentioning

confidence: 99%

Opines stimulate induction of the vir genes of the Agrobacterium tumefaciens Ti plasmid

et al. 1989

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Upon incubation of Agrobacterium tumefaciens A348 with acetosyringone, the vir genes encoded by the Ti (tumor-inducing) plasmid are induced. The addition of certain opines, including octopine, nopaline, leucinopine, and succinamopine, enhanced this induction 2-to 10-fold. The compounds mannopine, acetopine, arginine, pyruvate, and leucine did not stimulate the induction of the vir genes to such an extent. The enhancement of vir gene induction by opines depended on acetosyringone and the genes virA and virG. Opines stimulated the activity of the vir genes, the double-stranded cleavage of the T (transferred)-DNA at the border repeat sequences, and the production of T-strands by the bacterium. The transformation efficiency of cotton shoot tips was markedly increased by the addition of acetosyringone and nopaline at the time of infection.Phenolic compounds secreted by wounded plant cells can induce the activity of certain genes encoded by the Ti (ttmor-inducing) plasmid of Agrobacteriiin tuimeficiens (3,37,39 (42, 51) for such phenolic inducers as acetosyringone (37). The virG locus, which is expressed at a low basal level, is subsequently induced to higher levels of expression (38). This gene presumably encodes a transcriptional activator that induces its own expression and the expression of the genes 1i'rB, virC, virD, virE, and pinF (27,42,51). The virD locus encodes a T-DNA border-specific endonuclease (1,17,41,49,52,53) that nicks the T-DNA border repeat sequences on the bottom strand, generating single-stranded T-DNA molecules called T-strands (1,40,48). T-strands can be coated with a virE-encoded singlestranded-DNA-binding protein (6,8,11,15) and have been hypothesized to be the form of the T-DNA transferred to the plant cell (43). The virD endonuclease also generates doublestranded scissions at the T-DNA borders (17,47,48). The regulation of the genes *irC and virD by the chromosomal locus ros has also been described (9,10,44).Following insertion into plant nuclear DNA, T-DNA genes are transcribed and direct the synthesis of enzymes involved in the production of phytohormones and unusual low-molecular-weight compounds termed opines (for reviews, see references 2, 16, and 31). The phytohormones stimulate the uncontrolled proliferation of plant cells, resulting in tumors called crown gall tumors. Opines, which are crown gall tumor-specific compounds, are secreted into the rhizosphere where they can be used as an energy source by the inciting bacterium to the exclusion of most other soil microorganisms. It (45,46).We are interested in the relationship, if any, between opines and vir gene induction. We initially hypothesized that opines may inhibit the induction of these genes by acetosyringone. The rationale was that the bacterium would not induce the T-DNA transfer machinery if it sensed that a tumor, recognized by the presence of opines, had already been formed. The results presented below suggest that many opines do affect the acetosyringone induction of the vir genes. The effect, however, is to enhance r...

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Opine Synthesis in Wild-Type Plant Tissue

Cited by 41 publications

References 17 publications

Extended Host Range of Agrobacterium tumefaciens in the Genus Pinus

Extended Host Range of Agrobacterium tumefaciens in the Genus Pinus

Plant Cell Biotechnology

Opines stimulate induction of the vir genes of the Agrobacterium tumefaciens Ti plasmid

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